1. Field of the Invention
The present invention relates to a method for manufacturing a substrate over which a semiconductor layer is provided with an insulating layer positioned therebetween, and particularly relates to a method for manufacturing a silicon on insulator (SOI) substrate. Further, the present invention relates to a method for recycling a bond substrate in the manufacturing method of an SOI substrate.
2. Description of the Related Art
As substrates suitable for manufacture of semiconductor devices that achieve low power consumption and high-speed operation, attention has been directed to SOI substrates in which a semiconductor layer is provided over a base substrate having an insulating surface.
One of known methods for manufacturing an SOI substrate is a hydrogen ion implantation separation method (see Patent Document 1). The hydrogen ion implantation separation method is a technique of forming an SOI substrate in the following manner. An oxide film is formed on one of two silicon wafers which is to serve as a bond substrate, and by implanting hydrogen ions into the bond substrate, a microbubble layer is formed in the bond substrate. The bond substrate is put in close contact with the other silicon wafer that is to serve as a base substrate, with the oxide film positioned therebetween. Then, by a heat treatment, the bond substrate is split with the use of the microbubble layer as a splitting plane. Another heat treatment on the base substrate side forms a strong bond between the base substrate and a semiconductor layer that is separated from the bond substrate. Thus, an SOI substrate is formed.
Furthermore, for an efficient and economical use of silicon wafers, a method by which many SOI substrates can be manufactured with as few silicon wafers as possible has been researched (see Patent Document 2).